Imaging of cerebrospinal fluid leakage from the cribriform plate

Abstract

Cerebrospinal fluid leakage from the skull base occurs when the subarachnoid space communicates with the extracranial space. Cerebrospinal fluid leakage from the cribriform plate is often difficult to diagnose because the fistula is small. If the fistula can be identified before surgery, this can contribute greatly to treatment. We present 2 cases of cerebrospinal fluid leakage from the cribriform plate with tiny fistulas, which we were able to diagnose before surgery with CT and MRI.

Keywords: Cerebrospinal fluid leakage; Cribriform plate; Fluid accumulation in the sphenoid sinus; Meningocele; Olfactory fissure.

Fig. 1A

CT (a) Oblique coronal plane aligned perpendicular to the base of the skull. (b) Oblique sagittal plane aligned with the left olfactory fissure. (c) Oblique sagittal plane aligned with the right olfactory fissure. (d) Oblique axial plane aligned parallel to the base of the skull. Bilateral cribriform plates were indistinct, but it was unclear whether there were bone defects (a-c). A soft tissue density protruded from the cribriform plate in both olfactory fissures with left-sided predominance, which may have indicated the site of leakage (a-d). CSF leakage from the left side was suspected on the basis of the patient's symptoms and an air-fluid level in the left sphenoid sinus (c) (yellow arrowhead). 1B. MRI. (a) Coronal T2WI. (b) Coronal 3D-MR cisternography. (c) 3D-MR cisternography oblique sagittal plane aligned with the right olfactory fissure. (d) 3D-MR cisternography oblique sagittal plane aligned with the right olfactory fissure. (e) Gd-T1WI oblique sagittal plane aligned with the left olfactory fissure. Coronal T2WI showed a high signal intensity in the left olfactory fissure, which corresponded to the soft tissue density seen on CT (a) (arrowhead). On 3D-MR cisternography, the signal in the left olfactory fissure was unclear, and there was a high signal intensity continuous from the subarachnoid space to the right olfactory fissure (b and c) (arrows). Gd-TIWI showed a meningocele-like structure protruding from the cribriform plate on both sides (d and e) (arrow and arrowhead). 1C. (a) Axial CT image. (b) Axial T2WI MRI 3 hours after the CT images were obtained. (c) Axial CT image 4 days after the MRI images were obtained. (d) The air-fluid level in the left sphenoid sinus increased in size between the CT and MRI imaging, suggesting persistent leakage of CSF in the left cribriform plate (a-c) (arrowheads in b and c indicate the accumulating fluid collection). No air-fluid level was observed in the right sinus. 1D. Endoscopy A meningocele (arrowhead) measuring 1-2 mm in size was found in the left olfactory fissure during endoscopic surgery. CT, computed tomography; CSF, cerebrospinal fluid; MRI, magnetic resonance imaging; T2WI, T2-weighted imaging.

Fig. 2A

CT. (a) ) Oblique axial plane aligned parallel to the base of the skull. (b) Oblique coronal plane aligned perpendicular to the base of the skull. (c) Oblique sagittal plane aligned with the left olfactory fissure. (d) Axial plane. The left cribriform plate was unclear, and there was a soft tissue density continuous with the subarachnoid space (a-c) (arrowheads). An accumulation in the left sphenoid sinus was thought to be leaked CSF (d) (arrowhead). 2B. MRI. (a) Coronal T2WI. (b) 3D-MR cisternography oblique axial plane aligned parallel to the base of the skull. (c) 3D-MR cisternography oblique coronal plane aligned perpendicular to the base of the skull. (d) 3D-MR cisternography oblique sagittal plane aligned with the left olfactory fissure. T2WI and 3D-MR cisternography showed high signal intensity in the left olfactory fissure, suggesting fluid (a-d) (arrowheads). However, communication with the subarachnoid space was not evident. 2C. Endoscopy. A meningocele (arrowhead) between the left superior nasal turbinate and the nasal septum was observed. The fistula measured approximately 1-2 mm in size. CT, computed tomography; CSF, cerebrospinal fluid; MRI, magnetic resonance imaging; T2WI, T2-weighted imaging; 3D, three-dimensional.